The present invention relates in general to an apparatus designed to remove particulates from a liquid and, in particular, a method and apparatus for particulate removal utilizing a pressurized system in combination with a wedge wire screen filter.
Traditional filtration systems are usually made of a standard woven wire string or basket, perforated plate basket, mesh bags, granular media, sintered cartridges, centrifugal or cyclone separators. With the exception of the centrifugal and cyclone units, all of these systems operate in a submerged enclosure with particulates being trapped by the small openings or orifices in the filter element.
The submerged systems have several shortcomings: These systems all plug rapidly when heavily loaded and must be removed to be cleaned or require back flushing to remove debris and particulate. This requires substantial maintenance costs to service the submerged systems. All of these units rapidly lose filtration efficiency as debris becomes trapped in the filter and often require a high liquid pressure to function normally. Because of the thin layer of filtrate that is required to plug a normal filter element, the element must be replaced or cleaned frequently. As the process stream must not be interrupted, maintenance and cleaning often create a dangerous and unfavorable condition. Additionally, the filter element grids must be large enough to pass the liquid yet small enough to trap particulates. In some filter mediums, the uniformity of plugging is uneven resulting in areas of high velocity, plugging and breakthroughs. This inconsistent flow rate can affect the efficiency of the filtration system resulting in poor particulate removal from the liquid due to plugging and leakage.
The conventional, non-submerged systems also manifest several deficiencies: First, the liquid flow onto an inclined screen typically results in particulates becoming trapped in the filter, particularly at the upper surface area of the angled screen. This requires frequent cleaning and maintenance in order to assure efficient filtration. Non-submerged systems also tend to plug and have surface overflow, resulting in a lower efficiency and poor filtration. Further, they do not provide for uniform filtration of particulate matter.
It is desirable to provide for enhanced particulate removal, a self-cleaning filter as well as consistent velocity flow of the liquid by employing an elongated, pressure competent housing incorporating a Coanda tilted wire wedge wire screen as a filtration device which enables self-cleaning as well as the introduction of air into the system causing the filtration device to work under pressurized conditions and to regulate the water level for most effective removal of debris.